@jsteffenson wrote:
I have an R5 and an EF 100-400 L lens with a RF-EF converter and would like to try a 1.4x extender. I assume I should get an EF 1.4 extender to mount between the converter and the lens rather than RF extender to mount to the camera and then the converter. Can someone confirm? Thanks!
Yes, you need the EF teleconverter. If you try to work it out in your head, the RF seems like it should work, but when you have the devices in hand, which I do, you will find that the RF 1.4X teleconverter will not mount to the EF>RF adapter. The RF's elements extend too far into the adapter. I'm sure "not fitting" wouldn't be the only problem, but I'm no lens engineer 🙂
Newton
